In manufacturing a 2 in 1 note PC in which a built-in battery (hereinafter, referred to as a 2nd battery) is mounted on a Keyboard Dock (hereinafter, referred to as a KB Dock), even in a case where the PC is separated to only the KB Dock, when the KB Dock 2nd Battery is charged, a PeakShift function which stops a charging from an AC adapter and switches into a battery driving so as to suppress a power consumption is necessary in a time period which is high in a power consumption. However, the way of coping with such a demand has not been known yet.